Thallium occurrence and partitioning in soils and sediments affected by mining activities in Madrid province (Spain)

• Published in: The Science of the total environment Vol. 536; pp. 268 - 278
• Main Authors: Gomez-Gonzalez, M.A., Garcia-Guinea, J., Laborda, F., Garrido, F.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-12-2015
• Subjects: Ag–Cu ores; Bacillariophyceae; Cathodoluminescence; Environmental Monitoring; Mining; Soil - chemistry; Soil contamination; Soil Pollutants - analysis; Spain; Thallium; Thallium - analysis; ANE, Spain; Spain, Castilla, Madrid; Thallium; Ag–Cu ores; Cathodoluminescence; Soil contamination
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2015.07.033

Thallium (Tl) and its compounds are toxic to biota even at low concentrations but little is known about Tl concentration and speciation in soils. An understanding of the source, mobility, and dispersion of Tl is necessary to evaluate the environmental impact of Tl pollution cases. In this paper, we examine the Tl source and dispersion in two areas affected by abandoned mine facilities whose residues remain dumped on-site affecting to soils and sediments of natural water courses near Madrid city (Spain). Total Tl contents and partitioning in soil solid phases as determined by means of a sequential extraction procedure were also examined in soils along the riverbeds of an ephemeral and a permanent streams collecting water runoff and drainage from the mines wastes. Lastly, electronic microscopy and cathodoluminescence probe are used as a suitable technique for Tl elemental detection on thallium-bearing phases. Tl was found mainly bound to quartz and alumino-phyllosilicates in both rocks and examined soils. Besides, Tl was also frequently found associated to organic particles and diatom frustules in all samples from both mine scenarios. These biogenic silicates may regulate the transfer of Tl into the soil-water system.
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•Abandoned mine residues are Tl sources in soils of Madrid catchment area.•Tl was associated to quartz and aluminosilicates in both rocks and soils.•Tl was frequently found associated to organic particles and diatom frustules.•Cathodoluminescence is a suitable technique for Tl detection on soils and rocks